1. Field of the Invention
This invention relates to the production of laminated glazings and in particular to a device for the assembly of the constituent elements of a laminated glazing by pressing, in particular by calendaring, i.e., by passing the stack of said constituent elements (designated as glazing in the following description) between upper pressing means and lower pressing means.
2. Description of the Related Art
Known calendaring devices, described for example in French patent publication 2,053,104, are generally equipped with two series of pressing rolls or rollers: a series of lower rollers placed beside one another, their positions being independently adjustable to obtain a curvature corresponding to the desired crosswise curvature, which is generally the mean curvature of the glazing; and a series of upper rollers placed approximately in the same way. In known devices, the two series of rollers are each mounted on a crosswise beam belonging to a frame able to pivot around a horizontal axis, the whole constituting a mobile unit, so that the rollers remain approximately perpendicular to the glazing during the entire assembly operation. The adjustment of the original position of the pressing rollers can be performed by means of their system of mounting on the crosswise beam. This adjustment is delicate and time consuming because these devices are equipped with a large number of pressing rollers, generally between 30 and 40. These rollers must be adjusted in height and possibly in inclination, individually or in pairs, in relation to one another. The original position of the pressing rollers is generally adjusted according to the mean crosswise curvature of the glazing.
During the passage of the glazing between the rollers, the position of these rollers can vary to follow variations, when they are not very significant, of the crosswise curvature of the glazing, via their system of mounting by elastic or pneumatic means on the beam to which they are attached. A mounting device using pneumatic means and obtaining a great flexibility for the rollers is described in European patent publication 0,189,345. In this device, called a "floating" device, the compression chambers of the cylinders of the upper rollers and those of the cylinders of the lower rollers are in communication, so that the pneumatic pressure exerted on a pressure roller is equal to that exerted on a counter pressure roller.
These devices are generally suitable for the assembly of glazings exhibiting a slightly pronounced and regular crosswise bending and when this crosswise bending of the glazing is approximately the same over the entire length of the glazing. But for glazings with more complex shapes, particularly for glazings exhibiting a very deep bending in the crosswise direction and/or an irregular bending over the length of the glazing, these known devices are not always satisfactory because they are not flexible enough to be able to follow all the large variations in curvature of the glazing. If their pressure is too small, an insufficient or not very homogeneous adhesion of the constituent elements of the glazing results or, conversely, if their pressure is too high, breaking of the glazing results.
In addition, when going from one type of glazing to another type of glazing of different mean crosswise curvature, it is generally necessary to modify the original position of the rollers and therefore to redo the adjustment.